水闸运行对河流中氮污染物迁移转化与降解机制的影响

Effect of Sluice Operation on Migration,Transformation and Degradation Mechanism of Nitrogen Pollutants in Rivers

近年来,氮素超标严重影响了河流水环境质量,造成水质恶化与水体富营养化,已经成为我国河流的主要水污染问题。水闸升降引起的河流水动力条件变化会对河流中不同形态氮素的迁移转化产生影响,进而影响不同形态氮素的降解系数。以山西省丹河为研究对象,探究水闸运行下氮污染物的迁移转化与降解机制。研究成果表明,NH_(4)^(+)-N降解系数与河流流速相关性显著,线性回归方程为:K(NH_(4)^(+)-N)=5.894 v-1.753(R=0.867,p<0.001);NO_(3)^(-)-N、NO_(2)^(-)-N和TN的降解系数均与河流流速的相关性不显著。顺直河段开闸放水期间,NH_(4)^(+)-N、NO_(3)^(-)-N、NO_(2)^(-)-N和TN的降解系数比闸门关闭期间高出0.37 d^(-1)、0.43 d^(-1)、0.24 d^(-1)、0.72 d^(-1);弯曲河段开闸放水期间,NH_(4)^(+)-N的降解系数比闸门关闭期间减少0.4 d^(-1),NO_(3)^(-)-N、NO_(2)^(-)-N、TN的降解系数比闸门关闭期间高出0.67 d^(-1)、0.42 d^(-1)、0.87 d^(-1)。开闸放水和闸门关闭时,NH_(4)^(+)-N浓度在河流行进过程中表现为在顺直河段减小,弯曲河段增大;NO_(3)^(-)-N浓度和总无机氮浓度则在顺直和弯曲河段都不断减少;开闸放水较水闸关闭状态,河流在行进过程中总无机氮浓度下降更快,有利于无机氮的去除。研究成果有助于揭示水闸运行下河流的脱氮机理,可以通过优化水闸运行,提高河流氮污染物降解系数。

In recent years,excessive nitrogen has significantly affected the quality of river water environment,resulting in the deterioration of water quality and eutrophication,which has become the main pollution problem of rivers in China.The change of river hydrodynamic conditions caused by the lifting of sluices will affect the migration and transformation of various forms of nitrogen in the river,and thus affect the degradation coefficient of different forms of nitrogen.Therefore,this study focuses on Dan River in Shanxi Province to explore the migration,transformation and degradation mechanism of nitrogen pollutants under the operation of sluice.The results showed that NH_(4)^(+)-N was significantly correlated with the flow velocity,the linear regression equation is K(NH_(4)^(+)-N)=5.894 v-1.753(R=0.867,p<0.001),However,the degradation coefficients of NO_(3)^(-)-N、NO_(2)^(-)-N and TN were not significantly correlated with the flow velocity.In straight river section,degradation coefficients of NH_(4)^(+)-N、NO_(3)^(-)-N、NO_(2)^(-)-N and TN were 0.37 d^(-1)、0.43 d^(-1)、0.24 d^(-1)and 0.72d^(-1)higher than those during sluice-closing period.In the curved river section,the degradation coefficients of NH_(4)^(+)-N decreased by 0.4d^(-1),and the degradation coefficients of NO_(3)^(-)-N、NO_(2)^(-)-N and TN increased by 0.67 d^(-1)、0.42 d^(-1)and 0.87d^(-1),during the opening and releasing period of the gate,compared to the closing period.During the opening and closing of the gate,the concentration of NH_(4)^(+)-N decreased in the straight river section and increased in the curved river section,the concentration of NO_(3)^(-)-N and the total amount of inorganic nitrogen decreased continuously in the straight and curved sections.The total amount of inorganic nitrogen decreases faster when the sluice was opened than the sluice was closed.The research results are helpful to reveal the mechanism of nitrogen removal in rivers under sluice operation,and the degradation coefficient of nitrogen pollutants in rivers can be improved by optimizing sluice operation.